STUDIES OF SPACE CHARGE LOSS MECHANISMS ON THE ISIS

The ISIS Facility is the pulsed neutron and muon source based at the Rutherford Appleton Laboratory in the UK. Operation centres on the 50 Hz synchrotron, which accelerates ~3x1013 protons per pulse from 70 to 800 MeV, providing a mean power of about 0.2 MW. As commissioning of a second harmonic RF system is completed, it is expected that the main loss mechanisms will be related to transverse space charge forces, which are particularly strong during the multi-turn injection and trapping processes. Here, we describe progress in ongoing studies to understand more about what drives loss and thus limits intensity. Results from simulations and application of relevant theory are presented, concentrating on the effects thought most important for the ISIS ring. Progress on work looking at the half integer resonance and image effects in the rectangular vacuum vessels is reported, along with work for experimental studies.